Being ephimeral in nature, normally non additive gene effects do not contribute tangibly in the improvement of self pollinated crops (ALLARD 1960). However, complimentary interaction is fixable and utilizable genetic variance. Parents with good gca and per se are expected to express such complimentary effects in crosses and advanced progeny generations. Though, the crosses with significantly high sca and per se in desirable direction mostly involved at least one parent with good gca effects, however, crosses viz. T125 x 6TA204 (3 x 2), T130 x 6TA204 (4 x 2), TL56 x ST 69-1 (10 x 1) and Cinnamon x UPT74535 (18 x 4) involved both parents with good gca and per se for grain yield and its components, notably, harvest index, number of grains per spike, floret fertility and biological yield. Cross T130 x 6TA204 (4 x 2), interestingly, was found good for most of the yield components. Inclusion of these crosses in multiple crosses would greatly enhance the chances of transgressive segregants for characters related to yield and harvest index. In this context, intermating in segregating generation followed by selection would be a worth while approach. The extent of variation obtained with in the progeny of biparental cross or intermating in F₂ could well depend, in general, on the genetic diversity in parental stocks (HABGOOD 1983). For that matter, parents involved in these five crosses showed desirable (moderate) magnitude of genetic divergence (BEHL & SlNGH, 1986). Positive association between per se and sca effects suggested that selection for crosses with high sca could be based on per se also.

Selection for high harvest index without change in biological yield may have value for improving grain yield of cereals (ROSILLEY & FREY 1975). This is particularly relevant in case of Triticale where grain yield improvement has been realised mainly by increasing biological yield. Invariably lower harvest index in recorded in Triticale lines as compared to wheat. Further, in intervarietal crosses of hexaploid Triticale quite often varying degree of sterility may be expressed (THOMAS & KALTSIKES 1976) which lowers the grain yield and harvest index and therefore, deserves consideration during selection. Both the floret fertility and harvest index are yield attributing traits. Selection based on these characters would therefore, offer promise in selecting desirable lines.

Table 3. Specific combining ability effects and per se performance of seven best crosses


References

ALLARD, R.W. 1960. Principles of plant breeding. John Wiley and Sons, N.Y.

BEHL, R.K. and V.P. SINGH 1986. Genetic divergence in some triticale strains and their hybrids. Wheat. Inf. Service, 61 and 62: 46-50.

DONALD, C.M. & J. HAMBLlN 1976. The biological yield and harvest index of cereals as agronomic and plant breeding criteria. Adv. Agron., 28: 361-404.

HABGOOD, R.M. 1983. Genotype-environment interaction for predicting value of biparental crosses in Spring barley. Euphytica, 32(1): 273-280.

JENSEN, N.F. 1970. A diallel selective mating system for cereal breeding. Crop Sci., 10: 629-635.

JENSEN, N.F. 1978. Composite breeding methods and the DSM system in cereals. Crop. Sci., 18: 622-626.

KEMPTHORNE, O. 1957. An introduction to genetic statistics. John Wiley and Sons Inc., N.Y.

ROSILLEY, A.A. & K.J. FREY 1975. Estimates of selection parameters associated with harvest index in oat lines derived from a bulk population. Euphytica, 24: 121-132.

THOMAS, J.B. & P.J. KALTSIKES 1976. The genomic origin of unpaired chromosomes in triticale. Can. Genet. Cytol., 18: 687-700.

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